Effect of unbalanced voltages on static eccentricity fault diagnosis in induction motors

In this paper, an accurate method is proposed to detect static eccentricity (SE) in induction motors under unbalanced supply voltages. To accomplish this task, one important problem is dealt with: in stator current spectrum of induction machines, the frequency components characteristic of unbalanced supply voltages are similar to some of the frequency components caused by SE. In this direction, the present paper attempts to give an analytical explanation of the generation mechanism of all frequencies related to the SE in order to distinguish them from frequencies related to unbalanced voltages. The theoretical study and the simulation results have been verified by experimental tests conducted on a 1.1 -kW squirrel cage induction motor.